1. Field of the Invention
This invention relates generally to turbine driven electric generators, and is concerned in particular with the combination of an impulse type steam turbine supported on and closely coupled to an underlying electric generator by means of a common vertical shaft, with the shaft being rotatably supported exclusively by bearings contained in the generator housing.
2. Description of the Prior Art
In large commercial buildings and the like, steam is frequently employed as the energy source for the heating and cooling systems. Typically, the steam is received from an off site generating plant at a relatively high pressure on the order of 150 psig, and is reduced to around 15 psig by conventional pressure reducing valves before being conducted through the building services steam piping. In such cases, the energy lost during the pressure reduction process is not recovered.
In other cases, pressure reduction is effected by passing the steam through conventional horizontal shaft impulse type turbines flexibly coupled to horizontal electric generators, with the two units being mounted and aligned on a fabricated steel baseplate. The energy lost during pressure reduction is thus utilized to generate electricity. However, the net pay back is reduced considerably by high initial equipment costs, with the turbine/generator coupling and base plate being major contributing factors. Other drawbacks of horizontally disposed turbine-generator units include the fact that they occupy considerable floor space, and that the turbine-to-generator alignment required during installation and startup involves mechanical skills considerably above those possessed by typical building maintenance personnel.
It is also known to vertically couple turbines to electric generators. However, such arrangements are either overly complex and expensive, or are otherwise ill suited for use as simple, compact, low-cost energy recovery units which are functionally equivalent to conventional pressure reducing valves.
Accordingly, an object of the present invention is the provision of a close-coupled vertical-shaft impulse-type steam turbine-driven generator unit capable of functioning equivalently to a conventional pressure reducing valve, principally in but not limited to commercial buildings having steam heating and cooling systems. The electricity produced during steam pressure reduction may advantageously be used within the building electrical system to diminish electric power consumption from the local utility.
Another object of the present invention is the provision of a steam turbine-driven generator unit of compact design, which can easily be installed, operated and maintained by relatively unskilled building maintenance personnel.
Still another object of the present invention is the provision of a steam turbine-driven generator unit which is relatively inexpensive in comparison to known designs, thereby maximizing the payback realized from the generation of electricity.